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[avr-chat] Chip running too hot ?! :-/


From: Vincent Trouilliez
Subject: [avr-chat] Chip running too hot ?! :-/
Date: Mon, 25 Jun 2007 23:48:30 +0200

Hi,

I just happened to put my finger on my AVR chip, and notice that it's
quite warm indeed, even though none of the pins drive any significant
load (or any load at all at the moment, actually). I fear my numerous
experiments with the chip might have damaged it internally somehow and
some part of it might be overheating :-/ It appears to be functional
(avrdude can communicate with it), but that doesn't mean it's 100%
healthy inside...
Specifically, I did a few times lack concentration, and power off the
AVR BEFORE pulling the ISP programming cable (oh my god...), so
although avrdude can still talk to the AVR, the input stage of 
those pins might have suffered and now draw some current. Just
guessing.

It's an ATmega 32 (DIP package) running at 8 MHz (internal RC osc.) at 5
Volts. According to the datasheet under these circumstances it should
draw maximum 15mA, that makes for 75mW of dissipation. Now my finger is
by no means an accurate instrument to measure heat dissipation, but I
would have thought that 75mW in a large DIP package, would not
yield any heat my finger could sense easily. It's not so hot that I
can't keep my finger on it, but it's plenty warm enough to instantly
feel that it's well above ambient...

Anyway, if some could tell me how hot their chip runs, if hot at all,
so I know whether I should worry ! ;-)

Regards,

--
vince




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